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Rosetta and Philae in contact again

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19/06/2015

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42 comments

ESA and its Rosetta mission partners have confirmed that another communication link has been made between Rosetta and Philae today.

The signal was transmitted from Rosetta to ESA’s space operations centre in Darmstadt and received at 15:37 CEST on 19 June, and confirmed by the Lander Control Centre at the German Space Centre, DLR. A second signal was received at 15:54 CEST.

The downlink was stable; the two contacts received by Rosetta lasted two minutes each. Both delivered numerous packets of lander housekeeping and status data, 185 in total, which are still being analysed at the time of this writing. No science data were anticipated or received.

“We are very happy to have received signals from the lander again, and we are all working hard towards establishing a robust link between Rosetta and Philae,” comments Patrick Martin, ESA Rosetta mission manager.

This was the first signal received from Philae since 14 June. This was not unexpected, however, due to the pre-planned science operations of the orbiter, and its location around 180 km above the comet’s surface today.

In the meantime, new commands have been uploaded to Rosetta to further adjust its trajectory and distance from the comet to improve the radio visibility between the two spacecraft, with the first sets of thruster burns having taken place this past Wednesday and the next set planned for Saturday morning. The goal is to bring Rosetta to about 177 km from the comet nucleus and keep it in a range of latitudes that maximise opportunities for lander communication.

The Rosetta and Philae teams will be closely monitoring subsequent transmissions between the spacecraft, not only to better determine the health of the lander, but also to understand the length and frequency of available communication timeslots. This information is needed to determine when to upload new commands in order to restart science operations and, similarly, when the data can be downloaded.

Discussion: 42 comments

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AndrePosted on 19/06/2015 at 17:33

I am happy to see philae alive. Could you please try to answer the following questions:
These housekeeping data pakets were and will be generated all the time. How many pakets are generated during one earth day?
In which order do you recieve the pakets? Always the newest first? Or the oldest? Or can you decide?
Thanks and regards. Greetings from Germany.

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AlexPosted on 19/06/2015 at 19:18

This is a great question – hope it’s answered!

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Oliver KüchemannPosted on 21/06/2015 at 13:56

We receive roughly 150TM packets per comet day.
The Mass Memory Units are basically FIFOs, meaning that we get the oldest data first.

Grüße aus Köln, direkt aus dem LCC!

Oliver

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AndrePosted on 23/06/2015 at 13:21

Hello Oliver,
thanx for your answer. I am so curious about whats going on in the future with philae and rosetta. Keep up your work. I really love your work.
Also making science so literally touching is great. Thank you for beeing so communicative.
Regards
und Grüße ans Lander Control Center aus Dortmund!
André

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DanielPosted on 21/06/2015 at 20:14

Hi Andre:

We asked Armelle Hubault, one of the Rosetta engineers, for an answer to this. She replied:

The number of packets generated during 1 day does not mean much here, as the Lander is active (and generating data) only when it is illuminated.

It is producing housekeeping data at a rate of 52 bps.
The maximum speed of the link from Philae to Rosetta is 16 kbps.

The order the data is sent is First In First Out (at least in the current situation).

Cheers,
Armelle

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AndrePosted on 23/06/2015 at 13:02

Hello Daniel, Armelle,
thank you for your answer. I really appreciate that. I wish you and the rosetta team all the best. The story of Philae reminds me of the novel ‘the martian’ where so many people on earth where anxious about the destiny of Mark Watney.

Thanks again for answering the question.
André

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HenkPosted on 19/06/2015 at 17:42

Epic News! Lets hope the European Space Agency can get communication going once or even 2 times each earth day now (2 comet rotations/days per earth day) and with even higher throughput per contact. That could mean we can start seeing first uploads and first new science by the end of next week or certainly by the end of the month. Which following that would give ESA at least 12 weeks or 3 months!!! of new science operations! And with ever increasing solar power during the first half of that 3 month long period. Likely even 4 months and perhaps even going into 5 months! Which would certainly be enough time to at least get many good pictures (and 3d scans) back from the comet landing site. Now we basically had only 1 very good picture and a few less clear once in the shadows. We should have dozens of good pictures at the minimum. Not to mention increased data on all the other instruments. So exciting. Looks like the high risk of this lander part of the Rosetta mission could now also be paying of in an extremely big way for Science and for ESA accomplishments. Fingers crossed for the coming week.

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MargaritaPosted on 19/06/2015 at 17:57

Great news – I can stop holding my breath.
As ever, your promptness in keeping us informed is very, very much appreciated. I saw the tweets and followed the links here.

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RokPosted on 19/06/2015 at 18:16

Hi.

Any idea when we could expect to see more solid upload/download sessions?

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JoksmarPosted on 19/06/2015 at 18:22

Thanks for the info. Waiting the power levels and temperature, I wish all good.

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haraldPosted on 19/06/2015 at 18:27

Those cartoon drawings are so epic, please consider to make a big blogstory about the people creating them.

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DavePosted on 19/06/2015 at 18:49

Thanks Claudia – really appreciate these updates! please keep them coming as often as you can as there are plenty of us on planet earth eagerly anticipating the next piece of Philae news and you are our primary link to updates regarding Rosetta and the plucky lander. Whatever info you can glean from the ESA team, please post it as soon as you are able. Cheers.

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EmilPosted on 19/06/2015 at 19:14

I wander if the team is planning for making some “jumps” and moving the lander to a more pleasant place. Maybe when there is enough scientific data and when the charging conditions are going bad anyway. I don’t see a reason not to try if the lander is approaching its end and most of the scientific goals are achieved. This could prolong the mission by a month or two and we may get better pictures.

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DashPosted on 20/06/2015 at 08:45

Emil…from what I gather Philae would already be dead (March) if it has landed as foreseen in the open. Where it is (sheltered) it will not get so much radiation (=heat) and it may carry on working for quite a long time. If it gets enough power to charge the batteries it would be great. I don’t think the lander can “jump” – Claudia / ESA can you clarify?

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HarveyPosted on 20/06/2015 at 12:51

It has no ability to ‘jump’. It can rotate it’s body and lift it a little, but has no mechanism to ‘jump’. The previous ‘jumps’ we’re just bounces.
The gravity is so low that use of any mechanical device, such as the drill, or lift/rotation, could make the lander move in a probably very unpredictable way. More likely topple over than ‘jump’, so hazardous.

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DanielPosted on 20/06/2015 at 22:09

Well they were considering “jumping” in November, so I’d think its fair to call it jump. Maybe the mechanism to lift/lower the body would able to generate enough force to carry out some kind of jump? It’s either that or the flywheel that would be responsible. As you say though, unpredictable.
I have to admit that I too am curious if they would consider taking the risk. Especially when winter starts approaching again when lack of sunlight will become an issue that would doom the lander anyway.

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João PratesPosted on 19/06/2015 at 19:37

Great news, congrats to all ESA teams working on this mission!

The big question for me is to know if the rate/pace of energy spending is greater or lesser than the recharging rate.

One needs to remember that it took 7 months of minor solar irradiation to bring Philae back to life, but it could just take a matter of days or even hours to exhaust the battery again, and hence repeat the hibernation cycle.

Too many communications with nothing to say except house keeping is not a good thing. Radio consumes power, we need to use it wisely.

Cheers all,

-jprates

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Luke ColliePosted on 19/06/2015 at 20:56

As I understand it, the battery is not being used at all at the moment. It has to be warmed up before it will accept charging, and this hasn’t been tried yet. Each comet day (12.4 hr) Philae moves into sunlight, power increases until it boots up, then increases further until it can use the radio. If it detects a signal from Rosetta, it replies, tries to establish a data link, and reports on its status. Then the shadows move round and reduce available power again, until it has to go back into hibernation. This will repeat until a sufficiently reliable link can be established to tell Philae to do something else.

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DenisPosted on 19/06/2015 at 22:31

I think that’s correct, until now all operations are being done directly on solar array power, during the ‘day’.

From the press conference on Wednesday, they explained that first science measurements will be done like that, without using the battery at all.
Philae detects the day/night cycle and can be programmed to perfom specific measurements each day, saving the data when night is approaching. After a few days, connection with Rosetta is established to dump all the data collected over the last few days.

The battery is only needed for the more power-hungry operations (like drilling). In that case, they need to spend one (or more) days charging the battery, then one day doing the drilling using both solar array and battery power.

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masanoriPosted on 20/06/2015 at 11:47

But in fact. it seems too many news medias are reporting that as the comet has got closer to The Sun, Philae finally became able to recharge the battery enough to boot. Something we very often see in today’s news media, isn’t it.

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Alex McClymontPosted on 19/06/2015 at 22:26

Amazing news!! Do you have any documentary companies working with you?(Horizon for example) It would be great to see a two hour special at some point.

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RaarghPosted on 19/06/2015 at 23:23

So … no one at ESA reading these comments or replying?

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RodPosted on 19/06/2015 at 23:52

Given the larger size debris that apparently orbits comets, does Rosetta have some sort of close proximity radar or detection system that will let it automatically change direction to attempt to avoid a sufficiently large threatening object. ?
Or is the probability of a collision considered to low . Thanks ESA for the blog ! What a fantastic journey this is. The scientists ,engineers ,IT , technicians and organisers are brilliant!!!

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GeraldPosted on 20/06/2015 at 16:32

Collision probability is low for large junks.

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Pierre PaquettePosted on 20/06/2015 at 02:19

Excellent news from this part of the Universe! 🙂 Philae is a tough little one, and will continue to amaze us!
Congratulations to the whole team at the ESA, and to each and every engineer and technician who worked on the probe! Good job!

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Dan levinPosted on 20/06/2015 at 02:26

Hi,
Are you able yet to determine where Philae is on the surface?
Also, just as important, we need more T shirts with the cartoon series on them. Please?!?

I started wondering how many in Rosetta’s science team had expected that they were going to (have to) count this role of Rosetta in such amount at this time of the mission calender.

But still wondering why such short duration of radio link between Rosetta & Philae while Philae gets sunshine for 3 hours per comet day??

Whatever thrown out from 67P are blocking it??
Philae’s radio link antenna is covered by comet’s material?? (I mean, is it possible that some material tends to stick with the antenna while it does not tend to stick with solar arrays??)

If Philae is close to some cliff as it seems to be, communication will be possible only when the cliff does not block the communication. So I guess on top of the illumination of Philae and the Rosetta-Philae distance, the geometry also matters. As they don’t know exactly its location, I guess it’s difficult to put Rosetta in an orbit that optimize the viewing geometry. It should improve over time I guess, as they refine the Rosetta orbit !?

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PeterPosted on 21/06/2015 at 22:29

As the data is FIFO, it would be quite curious to know the time stamp of them, and of the 0 degrees. Are the 0 degrees in the real-time part of the packet?

We know the comet rotates at 12 hours per rev. But what is the trajectory of Rosetta? How lang lasts its rotation? I read once its trajectory is on the terminator (perpendicular to the sun, therefore). What is the rotation axis of the comet? Thanks.